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From: George Anzinger <george@mvista.com>
To: Jamie Lokier <jamie@shareable.org>
Cc: Nick Piggin <piggin@cyberone.com.au>,
	Guillaume Foliard <guifo@wanadoo.fr>,
	linux-kernel@vger.kernel.org
Subject: Re: Scheduler degradation since 2.5.66
Date: Mon, 15 Dec 2003 23:45:48 -0800	[thread overview]
Message-ID: <3FDEB82C.80908@mvista.com> (raw)
In-Reply-To: <20031216005251.GB3364@mail.shareable.org>

Jamie Lokier wrote:
> George Anzinger wrote:
> 
>>Try running the test with a requested sleep time of something less than 
>>0.999849 ms.  All this is for the x86 which is using this time to do the 
>>best it can with the PIT which can only get this close to 1 ms ticks.  You 
>>can even vary this number to see exactly where the round up actually 
>>happens.  Ah, life in the nano world :)
> 
> 
> Would it be better to program the PIT for lowest frequency that's >= 1.0ms.

Possibly.  I haven't attempted to analize it.  I do know it would make some of 
the math a bear.  Integers like to round down (read truncate) so...  But then, 
what we have isn't exactly fun :)

-- 
George Anzinger   george@mvista.com
High-res-timers:  http://sourceforge.net/projects/high-res-timers/
Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml


  reply	other threads:[~2003-12-16  7:45 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-12-14 19:48 Scheduler degradation since 2.5.66 Guillaume Foliard
2003-12-15  2:45 ` Nick Piggin
2003-12-15  4:18   ` Nick Piggin
2003-12-16  0:39     ` George Anzinger
2003-12-16  0:52       ` Jamie Lokier
2003-12-16  7:45         ` George Anzinger [this message]
2004-01-15  0:43       ` Bill Davidsen
2004-01-15  3:36         ` George Anzinger

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